J Korean Neurosurg Soc 37 : 422-426, 2005
KISEP
Clinical Article
Anterior Cervical Interbody Fusion with the
Carbon Composite Osta-Pek Frame Cage
in Degenerative Cervical Diseases
Kwang Wook Han, M.D., Joon Soo Kim, M.D., Kyu Hong Kim, M.D.,
Yong Woon Cho, M.D., In Chang Lee, M.D., Sang Do Bae, M.D.
Department of Neurological Surgery, Masan Samsung Hospital, School of Medicine, Sungkyunkwan University,
Masan, Korea
Objective : Different types of interbody fusion cages are available for use in the surgical treatment of degenerative
cervical diseases. The purpose of this study is to assess the technical feasibility, clinical efficacy and radiological
results of intervertebral fusion with a carbon composite Osta-Pek frame cage (Co-Ligne AG, Switzerland) following
anterior cervical discectomy.
Methods : 41patients (25males and 16females) with minimum 6months follow-up were included in the study.
Disc height, cervical lordotic angle, segmental angle, and fusion rate were assessed by lateral radiographs. In this
retrospective analysis, clinical outcome was assessed as evaluated according to Odom's criteria.
Results : Fifty-four cages were implanted in 30 single-level, 9 two-level, and 2 three-level procedures. The mean
disc height, cervical lordosis angle, segmental angle were 4.2±1.8mm, 23.5±7.2。
, 2.3±3.3。
pre-operatively and
5.3±2.1mm, 24.2±8.3。
, 3.8±3.5。at 6months after the surgery. Six months after surgery, there was radiographic
evidence of fusion in 92.7% (38/41) of the patients. According to Odom's criteria, 37 of 41 (90.2%) patients
experienced good to excellent functional recovery.
Conclusion : These clinical and radiological results suggest that the carbon composite Osta-Pek frame cages are
safe and effective alternative to autologous bone graft after anterior cervical discectomy for treatment of
degenerative cervical disease.
·Carbon cage·
·Osta-Pek·
·Anterior cervical discectomy.
KEY WORDS : Interbody fusion·
Introduction
T
he anterior approach to nerve root decompression and
interbody fusion, a surgical treatment for the degenerative cervical disease, enables direct approach to remove herniated disc and fuse bones to prevent recurrence and degenerative
change thus it is the most widely used surgical method and
especially in cases of monosegment, there has been many reports of successful autograft without the internal fixation1,6,13,15,29).
However, reports of displacement or collapse of graft fragment,
change in the cervical angle, or pain from the donor site lead
to many studies to find a stable material to obtain sufficient
disc space and spinal stability and reduce donor site related
complications2,14,28,34,36).
Received：October 29, 2004 Accepted：January 24, 2005
Address for reprints：Joon Soo Kim, M.D., Department of
Neurosurgery, Masan Samsung Hospital, School of Medicine,
Sungkyunkwan University, 50 Hapseong 2-dong, Masan 630522, Korea
Tel：+82.55-290-6183, Fax：+82.055-290-6899
E-mail : nkalzabi@netian.com
422 J Korean Neurosurg Soc 37
This study analyzes radiological findings and shows the
clinical efficiency and applicability of the anterior approach
using a carbon composite Osta-Pek frame cage, as a bone
replacement, for the interbody fusion.
Materials and Methods
B
etween October 2001 to March 2004, 55 patients with
degenerative cervical disease to underwent anterior
discectomy and interbody fusion with carbon composite OstaPek frame cage (Co-Ligne AG, Switzerland). Among them,
41patients could be follow up for at least 6months thus able to
report their cases to be analyzed using clinical data, and
radiological findings in this retrograde study. Radiological
images were taken before, just after, a month, 3months and
6months after each operation to measure the degree of cervical
lordosis, segmental lordosis, and disc space height. The gore
angle was used to determine the degree of the cervical lordosis,
which is created by two hypothetical lines drawn from the
posterior side of the second cervical vertebra to that of the 7th
vertebra13). The height of disc space was the distance between
KW Han, et al.
the mid-point of two endplates surrounding the fusion site in the
lateral cervical radiograph. The degree of segmental lordosis
was measured by the angle drawn that two perpendicular lines
of the upper and lower endplates of fused segment.
Six months After the operation, the lower density between
the bone graft and vertebra, existence of trabecular bridging
ossification, the mobility of space in flexion-extension radiographs were taken to determine the successfulness of the bony
fusion (Table 1).
All the cases were done in Smith-Robinson method and the
size of cage to be inserted were determined by that length
measured from the radiograph. To encourage the bone union,
in initial 17 cases, the bone material used to fill the cage were
taken from the patient's own iliac crest, the later 24cases used
commercialized allograft to avoid graft-site complications.
The patients started walking on 2nd to 3rd day of the operation
wearing soft prosthetics for 3months. The clinical outcome of
the surgery were measured using the Odom's criteria and were
categorized into excellent, good, fair, and poor25) (Table 2).
Table 1. Criteria of fusion status
Good : No motion on flexion/extension radiographs, no
radiolucent zones between the graft and vertebrae,
and trabecular bridging at both endplates
Average : No motion on flexion/extension radiographs, no
radiolucent zones between the graft and vertebrae
Poor : Motion on flexion/extension radiographs, radiolucent
zones between the graft and vertebrae, and no trabecular bridging at both endplates
Results
Clinical results
The clinical outcome of the surgery was determined by the
Odom's criteria and patients with either excellent or good
categories were able to function normally at home and work
thus accepted as a successful group. There were 21cases
(51.2%) that fit into excellent group, 16cases (39.0%) of
good, 3cases (7.3%) of fair and 1case with trisegments of
poor group thus the successful rate was 90.2%.
Clinical findings
The age distribution was from 34 to 70years old with mean
age of 47.5. There were 25cases of male and 16cases of females.
There were 14 cases each from 30's and 50's then over 60', 40's
and there were no one under 30. At the time of admission, 28
cases were diagnosed as cervical radioculopathy, 9cases of
myelopathy and 4cases with both of the symptoms. There
were 30cases of monosegement which was the most common
type, 9cases of bisegments, and 2cases of trisegments out of
54 total number of segments. In 28cases, the surgery was
performed the C5-6 level.
Radiological results
The average height of disc space was 4.2±1.8mm before
the surgery, 6.7±1.6mm, an increase in 159%, just after the
surgery, then progressively decreased to 6.2±1.8mm at
1month, 5.8±1.9mm at 3months, and 5.3±2.1mm, an overall
increase in 126% compared to the height before the surgery at
6 months after the surgery
The average angle of the cervical lordosis was 23.5±7.2。
before the surgery and decreased to 20.3±5.1。just after the
surgery, and then progressively increased to 22.8±7.5。at
1month, 23.2±7.7。at 3months, and 24.2±8.3。
, an overall
increase in 103% compared to the angle before the surgery at
6months after the surgery.
The average angle of the segmental lordosis was 2.3±3.3。
Table 2. Criteria of clinical results (by Odom. et al25))
Excellent : Complete relief of symptoms with full activity
Good : Partial relief of symptoms with full activity
Fair : Improvement but limitation of activity
Poor : No Improvement or deterioration after surgery
before the surgery, 5.3±2.1。
, an increase in 230%, just after
the surgery, then progressively decreased to 4.9±2.8。at
1month, 4.6±2.9。at 3months, decreased to 3.8±3.5。
, an
overall increase in 165% compared to the angle before the
surgery at 6 months after the surgery.
We decided the surgery to be successful if scored Good or
Average and there were 24cases that scored good and 14cases
of average, and 3cases of poor thus fusion rate was 92.7%.
Complications
Post-operative complications included 1case of temporary
dysphagia, 1case of mild graft migration, 2 out of 3cases of
hoarseness later improved but 1cases did not. Four cases out
of 17cases which received autograft complained of pain at the
donor site but alleviated within 6months. There were 5 cases
of the transplanted cage sunk into the vertebra body which
only occurred in patients with multisegments.
Discussion
H
erniated intravertebra disc is a result of the age related
degeneration, that is intravertebral disc undergo biological
and morphological changes causing cervical pain, neurological
symptoms, or dysfunctional spine and there are two types of
treatments. There are conservative treatments such as rest, physical therapy, or adminstration of non steroid anti-inflammatory
drugs and surgical treatment. Surgical treatment include only
disectomy through the anterior approach, combination of
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Cervical Interbody Fusion
removal and inter- body fusion method, and laminectomy and
laminoplasty through the posterior approach. Especially
disectomy and interbody fusion using the anterior approach is
relatively easy approach with less amount of blood loss, good
operative field and less restraint on post-operative spinal
mobility are some of the advantages to the approach thus the
most common method to be used11,33).
Since the introduction of the anterior approach to the cervical
spine in 1955 by Smith and Robinson32), the procedure was
continuously modified by Cloward10), Bailey2) and other authors.
However, in the case of cervical fracture, anterior approach by
itself result in migration of graft material, developed kyphotic
deformity thus Bohler et al5) performed internal fixation using
H-shaped plate. During 1970s, Orozco and Liovert26) used Hshaped plate to fixciate internally and in 1986 Morscher et al23)
attempted fusion used cervical spine locking (CSLP) system.
Currently various types of metal are being introduced. Comparing
the internal fixation using an metal plate with bone graft without
plate fixation, advantages are immediate stability to the spine,
maintain normal cervical curvature, shortening the fusion time,
prevent graft deformity however, there are complications
including a screw loosening, recurrence of the instability due
to screw fracture, esophageal perforation, swallowing difficulty
or pain, soft tissue or nerve damage during the surgery, delay
the surgical time, and limited post-operative spinal motion4,27,30).
Some of the authors in case of degenerative cervical spondylosis
and disc herniation involving a monosegment, did not perform
the interbody fusion but just the disectomy and its result compared
with ones with the interbody fusion method were not much
difference in the clinical symptom while lowering the risk of
complication thus denied the need for the metal plates16,38).
However, when performing disectomy without the interbody
fusion, there is delayed complication of kyphotic deformity
causing neck pain lasting long period of time, and narrowed
vertebral disc, causing recurrence symptoms related to the
narrowed neural foramen thus became less favorable and currently
it is common to limit the treatment to soft disc herniation of
monosegment24).
Authors have different opinion as to whether or not performing
the bone graft is necessary during the anterior approach to the
degenerative cervical spondylosis but currently it is accepted
that interbody fusion with bone graft regardless of the type of
the graft material should be performed. These bone grafts was
first attemped in early 1950s by Bailey & Badgely2) by collecting
the autograft from the iliac crest and Cloward10) used dowel
type graft, Smith & Robinson32) used Tricortical iliac crest graft,
Vail and Urbaniak35) used fibular bone graft for the interbody
fusion.
424 J Korean Neurosurg Soc 37
Despite the fact that using the autologous bone in interbody
fusion demonstrates high fusion rate, infection or pain at the
donor site, longer operative time are problems to be noted
thus new methods using allograft, xenograft, and synthetic
material were introduced. However, allograft has risk of
immune reaction and infection, xenograft have lower rate of
interbody fusion, thus replacement for the autograft with
similar rate of fusion, lower risk of infection and maintain
early spinal stability were studied thus synthetic materials
such as hydroxyapatite implants, bone morphogenic protein,
polymethylmethacrylate, biocompatible osteoconductive
polymer, titanium discs, and ceramics titanium or carbon
were introduced17,19,21,31,34). In this study, the Osta-Pek frame
cage which is a medical grade composite composed of long
fiber carbon encapsulated in a PEKEKK (polyetherketonetherketoneketone) matrix were used during the surgery.
Carbon cage consisted of similar elasticity as the bone thus
it is known to have stress shielding effect, and stimulated bone
formation and improving the quality of fusion8,37) and in the
animal studies, the cage enhanced the production of osteocalcine
and activity of alkaline phosphatase, growth of fibroblast20).
In addtion, the carbon cage is a wedged shaped which the
anterior side of the cage is higher then its posterior side thus
improving the spinal curvature to be more natural and have
more high radiolucency thus it is easier than metal cage to
determine the post-operative evaluation of interbody fusion.
Latest studies reported that the wedged shaped carbon cage
compared to cage used in the cloward procedure the complication
rate of kyphosis is lower, and higher anterior disc height3) and
Vavruch et al36) argued that the Carbon cage in the anterior
interbody fusion were better then autograft in maintaining the
disc height.
This study also showed that the degree of cervical lordosis
increased when comparing before (average of 23.5) and 6
months (average of 24.2。
) after the surgery. The height of the
disc space increased from the initial average height of 4.2mm
just after the surgery but decreased to 5.3mm 6months after
the surgery, that is the height increased by 1.4mm on average.
The fusion rate was 92.7% and in 3cases where the fusion did
not occur but the symptom did not aggravate. According to
Odom's criteria, 37 of 45 (90.2%) patients experienced good
to excellent functional recovery thus should expect a good
clinical result.
Hacker et al14) used only BAK/C cage which the success rate
was similar to that of autograft with plate but reported that the
surgical complication occurred as half as many (11.8% vs. 20.4%)
and donor site complication was 3% compared to 67% that of
autograft. Also Bartels et al3) reported that in patients with
KW Han, et al.
monosegmental degenerative cervical spondylosis only used
the cage without filling it with to prevent donor site complication
which resulted in fairly good clinical outcome and maintained
stability as well.
In addition, the procedure that used only the interbody fusion
cage did not affect adjacent organs such as the esophagus thus
were able to decrease the post-operative complications such
as dysphagia.
The post-operative complications in this study include 1case
of dysphagia, 1case of graft migration, 3cases of hoarseness,
and 4cases out of 17cases which received autograft complained
of pain at the donor site but all were alleviated within 6month
period.
Kim et al18) reported the height of disc space to be decreased
more after the surgery in multisegments compared to monosegment but did not correlate with the clinical symptoms, and
also Choe et al9) reported that decreased in the height of the
vertebral disc after the surgery did not affect the clinical outcomes after the surgery.
However, in this study there were 5cases with partial descent
of the cage at the graft-site and all went through multisegment
operations and clinical symptom of one of them worsened.
Therefore, when the operation must be performed on multisegments, the replacement material should be seriously examined and studied, and the need for additional use of internal
fixation should be further studied in the future.
Conclusion
T
he authors concluded that by using the carbon composite
Osta-Pek frame cage in anterior interbody fusion, the
disc height is reserved while not requiring an additional internal
fixation, and it has high fusion rate, and less donor site complications thus it is an effective therapy for the degenerative
cervical diseases.
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